1. Field of the Invention
This invention relates generally to apparatus for controlling an internal combustion engine, and particularly to such apparatus for controlling idle speed to a target or desired value.
2. Prior Art
According to a conventional idle speed control apparatus for an internal combustion engine, as disclosed in Japanese patent application provisional publication No. 54-76723, engine speed is detected, and flow rate of air passing through a by-pass of a throttle valve is controlled so that the deviation of the detected idle speed of the engine from a target idle speed is made zero.
However, such conventional idle speed control apparatus suffers from a problem that a desired follow-up control is difficult when a target idle speed is increased or decreased at the time of turning on and off an air-conditioner of a motor vehicle. Therefore, it is difficult to ensure sufficient output of an internal combustion engine when it is intended to reduce fuel consumption amount due to contradiction.